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authorAvi Kivity <avi@redhat.com>2011-02-03 15:07:07 +0200
committerMarcelo Tosatti <mtosatti@redhat.com>2011-03-17 13:08:30 -0300
commitf86368493ec038218e8663cc1b6e5393cd8e008a (patch)
treed4108bd01616b4cd511a314ea3b5dfc8ba50bd23 /arch/x86
parent217ece6129f2d3b4fdd18d9e79be9e43d8d14a42 (diff)
KVM: Fix race between nmi injection and enabling nmi window
The interrupt injection logic looks something like if an nmi is pending, and nmi injection allowed inject nmi if an nmi is pending request exit on nmi window the problem is that "nmi is pending" can be set asynchronously by the PIT; if it happens to fire between the two if statements, we will request an nmi window even though nmi injection is allowed. On SVM, this has disasterous results, since it causes eflags.TF to be set in random guest code. The fix is simple; make nmi_pending synchronous using the standard vcpu->requests mechanism; this ensures the code above is completely synchronous wrt nmi_pending. Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kvm/x86.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8575d85202d..bd59e8ede88 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -360,8 +360,8 @@ void kvm_propagate_fault(struct kvm_vcpu *vcpu, struct x86_exception *fault)
void kvm_inject_nmi(struct kvm_vcpu *vcpu)
{
+ kvm_make_request(KVM_REQ_NMI, vcpu);
kvm_make_request(KVM_REQ_EVENT, vcpu);
- vcpu->arch.nmi_pending = 1;
}
EXPORT_SYMBOL_GPL(kvm_inject_nmi);
@@ -5180,6 +5180,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
r = 1;
goto out;
}
+ if (kvm_check_request(KVM_REQ_NMI, vcpu))
+ vcpu->arch.nmi_pending = true;
}
r = kvm_mmu_reload(vcpu);